Changes of the TiO2 thin film electro-optical properties in the Ar and N2 glow discharge plasma due to effects of the electric field in plasma's sheath

Abstract

Titanium dioxide thin films were prepared on glass substrates by spin-coating sol-gel method. The samples were exposed to the N2 and Ar glow discharge plasmas. The properties of the crystal structure and electro-optical features were measured. The average crystallite size of the thin films was decreased at 30% and 41% by the plasma of N2 and Ar, respectively. We showed the changes in the charge distribution of the crystal unit cells and the chemical bonds’ characteristics that lead to alteration of the single-oscillator parameters. Due to the N2 and Ar plasmas, the third-order nonlinear susceptibility in long-wavelength was increased about 25% and 123%, respectively. An alteration occurred in the optical band gap through TiN formation on the surface of the TiO2 thin film in the N2 plasma. This empirical study illustrated more considerable changes in TiO2/Ar thin film, due to the stronger electric field in the sheath of Ar plasma.